Two former NFL all-stars, Gale Sayers and Dwight Clark, have reportedly been diagnosed with neurological conditions and at least one family is wondering if football contributed to their loved one's mental state.

Former Chicago Bears running back Sayers was diagnosed with dementia four years ago, according to a report in the Kansas City Star on Sunday.

Sayers, who 40 years ago became the youngest player ever inducted into the Pro Football Hall of Fame, had been living in a care facility the last few months, his wife, Ardie Sayers, told the newspaper. Ardie Sayers said she recently moved her husband back home.

She told the Star she believes the dementia began as far back as 2009, but she said Gale remains fine physically.

"Other people start making up stories, and people are asking about him more and more," she said. "People must know."

The newspaper said members of the Sayers family believe there is a connection between football and his dementia.

Sayers close friendship with Bears teammate Brian Piccolo became the subject of a Hollywood movie titled, "Brian's Song" which chronicled Piccolo's battle with cancer. Piccolo died of cancer in 1970.

Sayers played seven seasons in the NFL with the Bears, though the injuries that eventually led to his early retirement limited him to just five productive seasons.

He led the league in rushing twice and was a five-time first-team all-pro (1965-1969). He played just two games in 1971 before retiring during the 1972 preseason.

Clark, a former San Francisco 49ers receiver, said Sunday on his blog that he has ALS.

"I have ALS, also known as Lou Gehrig's disease," the Clark wrote. "Those words are still very hard for me to say."

Clark wrote that he was diagnosed with ALS (amyotrophic lateral sclerosis) in late 2015 after visits to six neurologists and three ALS specialists.

"The one piece of good news is that the disease seems to be progressing more slowly than in some patients," Clark wrote. "I'm going to fight like hell and live every day to the fullest."

The 60-year old Clark noticed a weakness in his left hand in September 2015.

"I was mildly paying attention to it because since my playing days, I've constantly had pain in my neck," Clark wrote. "I was thinking it was related to some kind of nerve damage because it would just come and go."

Clark, a two-time Pro Bowl selection, played nine seasons with the 49ers, winning two Super Bowls.